Extruding apparatus



Dec. 13, 1955 E. J. LARSEN 2,726,761

EXTRUDING APPARATUS Filed NOV. 21. 1951 2 Sheets-Sheet l F/G INVENTOR E. J. LARSEN ATTORNEY Dec. 13, 1955 E. J. LARSEN 2,726,761

EXTRUD IN G APPARATUS Filed Nov. 21, 1951 2 Sheets-Sheet 2 INVENTOR E. J LARSE/V ATTORNEY United States Patent Office 2,726,761 Patented Dec. 13, 1955 EXTRUDING APPARATUS Elmer J. Larsen, Parkville, Md., assignor to Western Electric Company, Incorporated, New Yerk, Y. 1., a corporation of New York Application November 21, 1951, Serial No. 257,551 7 Claims. (Cl. 207-4) invention pertains to extruding apparatus, and more particularly to seals for preventingleakage of metal from inteden'ng with the bearings and other moving parts of ametal extruding apparatus.

A typical extruding apparatus, used in the manufacture of lead-sheathed electrical cables, is the Pirelli type press,

illustrated and described in a Patent 2,076,200 to R. E. Horley. This apparatus includes stationary inner and outer cylindrical members between which there is located a screw-threaded impeller. Molten lead, or a lead alloy, is fed' through an opening in the outer cylindrical member to the impeller, which is rotated in such a manner as to force the lead forward through a die.

Since it is necessary to provide a finite clearance between two relatively moving parts, leakage of the lead, or lead alloy, Occurs through the clearances between the unthreaded portion of impeller and the stationary inner and outer cylindrical members. By chilling a small section of the unthreaded portion of the impeller, this lead is caused to solidify, and under ideal conditions there would be no further difficulties afforded by this leakage. However, due to various factors unavoidably present in the actual apparatus, such as eccentricity and out of roundness of the impeller and the slight static pressure head of the lead being introduced to the impeller, large strips of solidified lead work their way backward into bearings and other vital parts of the apparatus. These strips of lead interfere with the proper functioning of the apparatus and serious damage may occur when they become wedged between the bearings and their races.

Various means have been devised in come these difliculties. One suggestion has been to provide a tortuous path for the lead, thereby minimizing the passage of these strips into the Working parts of the apparatus. However, it has been found that this methml is not entirely satisfactory.

object of this invention is to provide new and improved extruding apparatus.

Another object of this invention is to provide new and improved seals for preventing metal from interfering with the bearings and other moving parts of a metal extruding apparatus.

Other objects and features of this invention will become apparent as the specification proceeds. One apparatus illustrating certain features of this invention may include a barrel provided with a bore, a rotatable impeller positioned within the bore and having a front portion provided with helical threads and a rear portion thereof unthreaded and fitting closely within the bore, means for rotating the impeller to force a material through the bore toward the exit end thereof and masticating means for comminuting any material which may escape backwardly between the unthreaded portion of the impeller and the barrel. 7 i

Fig. l is'a fragmentary, vertical sectionof an extruding apparatus embodying features of this invention;

Fig. 2 is a fragmentary section taken along line 22 of Fig. 1, and

an attempt to overg Fig; 3 is a fragmentary section taken along line 3-3 of Fig. 1. V

The extruding apparatus illustrated in Fig. 1 includes a rotatable, screw-type, cylindrical impeller 10, the righthand portion of which is provided with helical threads 12-12 on both the inner and outer surfaces thereof. The impeller 10 is mounted for rotation between a barrel 15 and an elongated stationary sleeve 17. A sleeve bush.- ing 18 and a split bushing 20 positioned between the unthreaded portion of the impeller 10, and the barrel 1-5 and sleeve 17, respectively, afiord. bearing surfaces. for the rotating impeller 10.

The unthreaded portion of the impeller 10 is prolonged and projects from the barrel 15, through the bearings 18 and 20, into a bore 24- provided in. a. housing. 22. The impeller 10 is supported by a. thrust bearingZS anda roller bearing 26, which are positioned within the bore 24. The roller bearing 26 is retained within a recess in the impeller 10 by an annular flange 28- threadedly mounted thereupon. Suitable driving; means (not shown), mounted within the housing 22, is operatively connected for rotation of the impeller 10, by a gear 29 fixedly mounted thereupon.

The barrel 15 is secured to theright end of the housing 22 by bolts 30-30, and is provided with an inlet 31 through which molten lead, or lead alloy, is introduced into the. helical threads 1212 of the impeller 10. In order that the lead may reach both. the inner and outer faces of impeller 10, apertures 3333 are providedv therein. The unthreaded portion of the impeller 10, adjacent to the bushings 18 and 20, is provided with a. series of spaced annular grooves 35-35. on the inner surfacethereof and similar grooves 3636 on the outer surface. thereof. These grooved portions of the impeller 10 are designed to cooperate with the sleeve bushing 18 and split bushing 20 to assist in the formation of lead seals for preventing the molten lead, introduced to the screwthreaded portion of the impeller, from leaking backwardly between the impeller 10- and the barrel 15 and the sleeve 17.

Immediately adjacent to and to the rear of the grooves 3636, there is positioned a set of masticating rings 37 and 33. The outer masticating ring 37 is held stationary by being threaded into a cylindrical extension40 on the rear of the barrel 15. The inner surface of the ring 37 is formed with a flanged projection 41, which is provided with a multiplicity of teeth 4242 (Fig. 2) evenly spaced around the periphery thereof. The inner masticatingn'ng 38 is made in two sections, 44 and 45, thereby facilitating its mounting within an annular recess 47 in the impeller 10. The sections of the ring 38 are. secured to the impeller 10 by set screws. The outer surface of the ring 38 is formed with a flanged projection 48,. which is similarly provided with a multiplicity of spaced teeth 49 49 (Fig. 3).

The rings 37 and 38 are mounted so that the flanged projection of one ring is positioned directly opposite the unflanged portion of the other ring, as shown in Fig. 1. It is readily apparent from this arrangement, that any strips of solidified lead, which may work their way through the lead seal, must pass between the teeth 4242- and 49-49 ofthe rings 37 and 38, respectively, before they can reach the interior of the bore 24.

A conduit 50 located in the top of the housing. 22 communicates with the interior of the bore 24 and provides an inlet for the introduction of a coolant fluid (e. g. oil) thereto. A stream of fluid entering the bore 24 through the conduit 50 is separated into two parts by the annular flange 28. A portion of; the fluid is diverted into the roller bearing 26 for lubrication, while the remaining fluid is used to cool a section of the unthreaded portion of the impeller 10 adjacent to the grooves 35-35 and tion of the operation of the extruding apparatus.

This fluid chills the impeller has leaked thereinto to solidify,

1 38 are so positioned that any through the clearance '36 36. The coolant fluid serves another important purpose, as will become apparent from the following descrip- Provisions have been made for the removal of the coolant fluid from the bore'24 by means of a drain 52 formed in the barrel 15, which communicates with the lower interior portionof the bore 24.

Operation The extruding apparatus heretofore described is utilized 'to extrude a sheathing of lead, or a lead alloy,

around a continuous length of electric cable. Molten lead is fed through the inlet 31 under the. pressure of a slight static head, {approximately 30 p. s. i.),-to the helical threads 12-12 on the rotating impeller 10. The apertures 33-33 provided in impeller 10, as previously mentioned, allow access of the lead to both the inner and outer faces of the impeller. The impeller 10 forces the lead forward through a die (not shown) in a plasticcondition, about a cable 'core (not shown), whlch is fed through the stationary sleeve 17.

' Lead in a molten state exhibits a great propensity for leaking through extremely small constrictions. Hence, some of the molten lead which enters through the inlet 31 seeps through a clearance 55 between the unthreaded portion of the impeller 10 and the bushing 18, and through the clearance 57 between the impeller 10 and the bushing 20. Since it has been found that a minimum amount of leakage through clearance 57 may be tolerated without causing difficulty, it will not be necessary to consider its effect. However, leakage of lead through the clearance 55 is a major problem, since it is possible for the lead to gain access to the roller bearing 26 and cause serious damage thereto, as well as operating difliculties due to power surging.

A continuous supply of coolant fluid is introduced to the interior of the bore 24 by means of the conduit 50. in the vicinity of the clearances 55 and 57, and causes the molten lead that forming a lead seal, which comprises a thin cylinder of lead, within each of the clearances 55 and 57. It has been found that the grooves 35-35 and 36-36 aid in the formation of the leadseals and thereby effectively reduce the leakage of the lead through the clearances 55 and 57.

Howevenbecause of the inherent out of roundness 10f the'impeller 10 andthe small amount of eccentricity .that invariably exists in the rotation thereof, the widths of the clearances 55 and 57 at a particular point are alternately changing through maximum and minimum .di-

mensions. This produces a squeezing action on walls of thethin cylinders of solidified lead, which have formed in the clearances 55 and 57. Since lead is a very ductile uous runs of the extruding apparatus, these strips of lead accumulate and are forced backwardly by subsequently formed strips.

As previously mentioned, the masticating rings 37 and lead passing backwardly 55 must pass between the teeth 42-42 and 49-49. The ring 37 attached tothe barrel is necessarily stationary, while the ring 38 secured to the impeller 10 is rotating therewith. Thestationary teeth 42-42 and the rotating teeth 49- 49 cooperate to masticate the strips of lead passing therebetween into small chips. These chips pass into the interior of the bore 24, where they are flushed out through the drain 52 by the stream of coolant fluid, which enters via the conduit 50. The fluid carrying the lead chips is prevented from entering and fouling the bearing 26 by the annular flange 28, A suitable filtering andpumping means (not 'shown) connected to the drain 52 bya hose 60 removes the chips and other foreign matter from the discharged fluid and returns the filtered coolant fluid to the conduit It is to be understood that the term lead, as used in the appended claims, is meant to describe lead or extrudable lead alloys.

It will be manifest that the invention is not limited to the particular apparatus descr'bed, since various modifications can be made without departing from the spirit and scope of the invention.

What is claimed is: p

1. Apparatus for continuously extruding lead sheathing, which comprises a barrel provided with a'bore, an impeller mounted for rotation within said bore, means for rotating the impeller to urge lead along the bore toward the exit end thereof, a masticator provided at the rearend of the barrel, a complementary masticator mounted on the rear end of the impeller and rotatable therewith, said masticators cooperating to granulate any solidified lead which may be forced backwardly between the barrel and the rear end of the impeller, and means for circulating a stream of fluid through the apparatus for removing the granulated lead from the interior thereof.

'2. An apparatus for extruding lead, which comprises stationary inner and outer cylindrical members, a rotatable screw-type impeller positioned for rotation be- 3. In an extruding apparatus, which includes an outer .7

barrel provided With a longitudinal chamber, an impeller mounted for rotation within the chamber and having a front portion provided with screw-threads and a rear portion which is unthreaded and fits closely within the chamber of said barrel, driving means for rotating the impeller, means for cooling a section of the unthreaded portion of the an inlet through which a material may be introduced to the impeller, whereby it is urged forward within the chamber toward the exit end of the barrel, and means for masticating anyjsolidified material which may be forced backwardly between the unthreaded portion of 'the impeller and the walls of the chamber, which comprises a multiplicity of teeth provided on the walls of the cham her, and a multiplicity of teeth provided on the rotating impeller for cooperation with the teeth on the walls of the chamber to comminute any solidified material which may pass therebetween.

4. An apparatus for extruding lead, which comprises inner and outer cylindrical members, a rotatable screwtype impeller positioned for rotation between said mem bers and having a front threaded portion provided'with' helical threads and a rear unthreaded portion which fits closely within and around the inner and outer members,

respectively, roller bearings mounted on the unthreaded portion, a housing for retaining saidbearings and a, driving means forrotating' the impeller, a stationary toothed masticator mounted on the outer cylindrical member, and a complementary toothed masticator mounted'on the impeller intermediate of roller bearings andthe threaded portion of said impeller for cooperation with the masticator on the outer cylindrical member to comminute .strips of solidified lead which may be forced backwardly between the unthreaded portion of the impeller and the outer cylindrical'member. I

5. An extruding apparatus, which comprises a barrel provided with abore, a rotatable screw-type impeller,

the front portionof which is provided with threads and the rear portion of which is unthreaded and fits closely impeller, the barrel being provided with V within said bore, driving means operatively connected to the impeller for rotation of the impeller to force a working material forward within the bore until it is extruded at the exit end thereof, a ring mounted on the barrel in coaxial relationship with the bore provided therein and having a multiplicity of teeth formed on its inner surface, and a second ring mounted upon the impeller for rotation therewith and having a multiplicity of teeth formed in its outer surface, said rings cooperating to masticate any solidified material which may escape backwardly between the unthreaded portion of the impeller and the barrel.

6. An apparatus for extruding lead, which comprises a barrel provided with an axially extending bore, a screwtype impeller positioned for rotation Within said bore and provided with an unthreaded portion which fits closely within the rear end of the bore, means for rotating the impeller to force lead along the bore toward the forward end thereof, and a toothed pulverizer for comminuting any solidified lead which may be forced backwardly between the unthreaded portion of the impeller and the barrel.

7. An apparatus for extruding lead, which comprises a barrel provided with an axially extending bore, a screwtype impeller positioned for rotation within said bore and provided within an unthreaded portion which fits closely within the rear end or" the bore, means for rotating the impeller to force lead along the bore toward the forward end thereof, a toothed pulverizer for comminuting any solidified lead which may be forced backwardly between the unthreaded portion of the impeller and the barrel,

and means for directing a stream of fluid toward the pulverizer to carry the comminuted lead therefrom.

References Cited in the file of this patent UNITED STATES PATENTS 1,882,757 Boynton Oct. 18, 1932 2,076,199 Horley Apr. 6, 1937 2,076,200 Horley Apr. 6, 1937 2,108,529 Dunsheath Feb. 15, 1938 2,142,526 Norris Jan. 3, 1939 2,204,961 Grieve June 18, 1940 

6. AN APPARATUS FOR EXTRUDING LEAD, WHICH COMPRISES A BARREL PROVIDED WITH AN AXIALLY EXTENDING BORE, A SCREWTYPE IMPELLER POSITIONED FOR ROTATION WITHIN SAID BORE AND PROVIDED WITH AN UNTHREADED PORTION WHICH FITS CLOSELY WITHIN THE REAR END OF THE BORE, MEANS FOR ROTATING THE IMPELLER TO FORCE LEAD ALONG THE BORE TOWARD THE FORWARD END THEREOF, AND A TOOTHED PULVERIZER FOR COMMINUTING ANY SOLIDIFIED LEAD WHICH MAY BE FORCED BACKWARDLY BETWEEN THE UNTHREADED PORTION OF THE IMPELLER AND THE BARREL. 